/Engine/Plugins/Animation/RigLogic/Source/RigLogicLib/Public/dna/layers/GeometryReader.h
blendShapeTargetIndex must be less than the value returned by getBlendShapeTargetCount.
std::uint32_t getBlendShapeTargetDeltaCount ( std::uint16_t meshIndex, std::uint16_t blendShapeTargetIndex ) const